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[up2ng]

I have a 1998 Catera 3.0 and it seems that the Oil Cap & Filler Tube have a mild milky coating on it. now comes the twist there is NO oil in the coolant or Milky stuff on the dipstick and the last oilchange the oil was brown only.

It seems to me that steam is getting into where it shouldn't be but short of seeing the crossover and oil cooler going south.

Does anyone have any advice or ideas ?

[Dazzler]

Are you doing alot of short runs in it by chance??
When was the oil last changed??
Its basically condensation.

[up2ng]

no short runs
i'll give an example, did an oil change saturday and cleaned the cap and tube. 300 miles later some came back and if I look down the oil pipe it looks "steamed".

One thing I didn't put in the original post was that overnight the upper rad hose collapses and kinda goes flat but after running for a couple of minutes it goes back to normal. i dont get it

[Grumpy]

no short runs
i'll give an example, did an oil change saturday and cleaned the cap and tube. 300 miles later some came back and if I look down the oil pipe it looks "steamed".

One thing I didn't put in the original post was that overnight the upper rad hose collapses and kinda goes flat but after running for a couple of minutes it goes back to normal. i dont get it

I would replace your coolant expansion bottle cap.
As well as regulating the pressure in your coolant system,
and allowing for expansion as your coolant heats up, the cap
also has a negative pressure facility. As your coolant cools
and contracts overnight it takes up less space. Unless your
cap allows air to flow back in, you will tend to get a negative
pressure in your cooling system.

In your case, if the cap is faulty, the top hose is collapsing
instead, to decrease the volume that your coolant system
requires as it cools.

Ref the mayo in your filler cap, as 'Dazzler' said, this is normally
condensation.

If you are not doing short runs, check that engine is getting
up to temperature. If it is, try a different semi synthetic oil at
your next oil change.

[Marks DTM Calib]

Ok.

On a V6 it is NORMAL!

Reason:

When you burn fossil fuels you get water as a by product. As all pistons engines have some blow by gasses past the rings (even when new) you get some water that gets into the crank case.

This then evaporates off when the engine is warm.

Most goes through the crank breather system but, there is one other high spot it can gather and this is in the oil filler neck.

On most cars, the oil filler gets oil wash from the cams rotating but, on the V6 the oil neck is extended to improve access for oil filling so it does not get washed by the cams.

So you get condensed water mixed with a bit of oil the result of which is what you are seeing.

Notes:

1) If you go on a longer journey the engine and bay get much hotter and the mayo tends to disperse

2) Some oils are more prone to causing the condensate than others.

So, worry yeh not!

[up2ng]

how tight should the rad cap be.
i pretty much turn it until it cant turn anymore

[batista]

did you give it an engine flush before putting new oil in.

[Grumpy]

how tight should the rad cap be.
i pretty much turn it until it cant turn anymore

Just hand tight, so that it seals.
If you take the cap off and have a look at it, you'll see a black
centre piece with 2 small holes in it. This is the 2 way valve.
The valve will vent out if there is too much pressure in the system,
and vent inwards if a vacuum starts to form.

If you look at the screw threads around the inside of the cap,
you'll see 4 vertical cut outs. The 2 way valve connects the system,
by-passing the cap seal, when it reaches an over or under pressure
condition.

Seeing as your top hose is collapsing as the coolant cools and
contracts, this is indicating that the seal is holding the pressure,
but the valve is failing to open when an under pressure condition
occurs.

The top hose gets all the heat, so goes through a greater cycle
than the bottom hose, so tends to soften first. This is why you
are seeing your top hose flatten.

Replace the cap.

As previous posters have stated, unless you're getting other symptoms
that you haven't told us about, your slight mayo in the filler cap is
normal.

As previously stated, some oils are more susceptible than others
to this. So if it's bugging you, try a different semi sythetic oil at
the next change. But don't waste money doing the change early.
It really is no big deal.  

[up2ng]

There is Steam coming out of the oil spout when I remove the cap and the engine is running. I am losing coolant too but it isn't going to the floor.

I am waiting for the Rad Cap to come in and I have a bad feeling about this.

[hotel21]

Get things into perspective.

Oil will condense/emulsify as previously explained upon the filler cap/neck if the engine does not get hot enough to evaporate the water.  The water/oil mixture creates mayo....

The steam coming out the filler cap is most probably oil fumes due to breahter problems.

How much water loss is being discussed?  Yes, it should not loose any but depends on what other work has been done to the vehicle meantime....

[up2ng]

water loss is about  half of the expansion tank (light comes on) 200-300 miles.

I recently replaced the HBV because of a leak, and have not seen another leak so I was suprised when I needed coolant. the first thing I thought was that the oil cooler went but there is no sign of anything mixing together.

I'm clueless

[hotel21]

You are obviously thinking cylinder heads but these rarely fail on the V6's.  Rarely, but not unheard of, that is....

check the following ....

http://www.omegaowners.com/forum/YaBB.pl?num=1209123016

then consider your available options....